Ray Kurzweil is arguably the world's most famous futurist. He laid out the law of accelerating returns, which states that technology improves at exponential rates, and made a string of dead-on predictions about computing in the 80s -- that a computer would beat a man at chess by 1998, and that the world would link networks into some crazy globally connected system sometime in the mid-90s. Now, Kurzweil is talking solar. In an interview with Grist, he explains why he's not worried about climate change, and how renewable energy sources will become dominant much, much sooner than we think. He explains his techno-optimism to Grist:

One of my primary theses is that information technologies grow exponentially in capability and power and bandwidth and so on. If you buy an iPhone today, it's twice as good as two years ago for half the cost. That is happening with solar energy -- it is doubling every two years. And it didn't start two years ago, it started 20 years ago. Every two years, we have twice as much solar energy in the world. Today, solar is still more expensive than fossil fuels, and in most situations it still needs subsidies or special circumstances, but the costs are coming down rapidly ... we are only a few years away from parity.

So right now it's at half a percent of the world's energy. People tend to dismiss technologies when they are half a percent of the solution. But doubling every two years means it's only eight more doublings before it meets a 100 percent of the world's energy needs. So that's 16 years. We will increase our use of electricity during that period, so add another couple of doublings: In 20 years we'll be meeting all of our energy needs with solar, based on this trend which has already been underway for 20 years.

That's some major optimism indeed -- unfortunately, even if the technology itself got good enough that quickly, it in no way accounts for the massive task of deploying enough solar farms fast enough to render coal and natural gas plants obsolete. Many scientists say, after all, that we're going to need to drastically scale down emissions in 10 years time before we irrevocably alter our climate.

Finally, the most glaring miscalculation I think Kurzweil makes is that unlike the computing industry, there's an entrenched, powerful industrial opposition to clean energy that will actively work to stymie its advances whenever feasible in the political arena. Computers were developing into a wide open space in the market, with no comparable oppositional industry ready to compete with them -- the typewriter industry doesn't exactly have the same clout as the coal and oil industries. Perhaps if there wasn't a preexisting, artificially cheap energy source that was widely relied upon, and whose operators had access to major power levers, Kurzweil's time line could come true -- but since there is, we won't see the same kind of investment, excitement, and innovations in clean tech until use of dirty fuels is formally discouraged.